core

### Constructing a Best Fit or Best Fit Recompensate Sphere

You can construct a "best fit" sphere using five or more features. The best fit construction method takes the actual measured points, rather than the ball's center (as is the case of best fit recompensate). In both cases, PC-DMIS computes a least squares sphere, one for which PC-DMIS minimizes the average squared distance from the data points to the sphere.

To construct a Best Fit or a Best Fit Recompensate Sphere:

1. Select Insert | Feature | Constructed | Sphere to display the Construct Sphere dialog box.

2. From the Construct Sphere dialog box, select either the Best Fit or Best Fit Recompensate option (shown as Best Fit and BF Recomp ).

3. From the list that appears, choose the type of construction. For information on the different types, see "Best Fit Type (for Sphere)".

4. Select five or more features.

For Best Fit (BF) or Best Fit Recompensate (BFRE) constructions, while you can use any feature type for your input features, BF and BFRE fit types are typically used with point features or point sets (a scan of points, a feature set with points, or an expression that resolves to an array of points).

For Best Fit Recompensate, one of the five features must be a point.

5. Click the Create button.

The Edit window command line for this option would read:

CONSTR/SPHERE,BF,feat_1,feat_2,feat_3,feat_4,feat_5...

(Uses the actual measured points for construction.)

or

CONSTR/SPHERE,BFRE,feat_1,feat_2,feat_3,feat_4,feat_5...

(Uses the center of the probe for measurement.)

A - Best fit sphere constructed from five points.

Constructing a Sphere from five or more points